I used both Backblaze Personal and Arq in the past, but stopped using Backblaze recently.
They were always very political in what they didn’t back up (Finder tags…), but given their low pricing I kept using the product in addition to Arq (I would never have been comfortable with Backblaze as my main remote backup). Due to missteps stacking up over the last 12 months or so, I canceled my subscription.
The main issues bothering me are related to security & software quality and their politcal stance against backing up metadata. You can find their developers on Reddit saying noone should use tags for instance and just name files differently and use strict folder structures.
Some links…
My other concern is that Backblaze doesn’t actually back up everything. It fails all but one of the Backup Bouncer tests, discarding file permissions, symlinks, Finder flags and locks, creation dates (despite claims), modification date (timezone-shifted), extended attributes (which include Finder tags and the “where from” URL), and Finder comments. (Source)
(Source)